The present invention relates to an apparatus used for protectively encasing wooden piles to reduce marine borer attack, abrasion and other structural damage. Piers, wharfs, and other structures extending from a shore or free-standing in a body of water are commonly supported by wooden piles. Immersion of wooden pile in seawater and a marine environment exposes the pile to marine borer infestation and abrasion damage. The present invention provides an encasement around a pile to create an environment of stagnant water between the pile and the encasement that is toxic to borers. Marine borers can destroy a creosote treated pile in less than 6 years. In heavily-infested waters, the timber will receive attack from the mud-line to high tide levels.
Various devices and methods have been used in the past to protect piles. One of the oldest methods of protecting piles is to soak wooden piles in creosote or tar. However, the tar soon wears off. Further, the use of creosote in this way raises environmental concerns.
More recently, devices and methods using sheeting of various materials has been employed. It is important to choose an appropriate material for the protective sheeting. For example, some protective coverings employ polyvinyl chloride plastic sheeting. Such PVC sheeting is not stable in the presence of creosote and deteriorates and becomes brittle over time. Fiberglass-reinforced plastic, on the other hand, is generally pre-formed and will not conform to surface imperfections and variations in the shape and diameter of pilings.
Piling encasement devices known in the art are secured by belts, rings, tongue and groove means, heat seals, hook and eye means, and bolts have been used. Such methods of securing a sheet to a pile have proved unsatisfactory. Most pile coverings secured in these ways do not produce a proper seal and permit too much circulation of seawater next to the piling allowing marine borers to survive and multiply. Further, most of the above sealing means are not stable in the presence of creosote, or do not stand up to the variations in seawater temperature or to turbulent wave action. The mere use of sheeting and nails is not sufficient because wave action can tear the sheeting away from the piling. Heat sealing, used most often with steel pilings but also used with wood, presents problems in water with varying temperature: where the water is cold near the bottom of the piling, the seal does not form; and where the water is warm near the surface, the heat is too intense and the sealing or sheeting material can be destroyed. Additionally, heat sealing utilizes both heat and pressure to form the seal. Due to surface imperfections and variations in the shape of wood piles, uniform pressure is difficult to achieve.
Further, some methods of sealing do not allow for a large variety of sheet thicknesses to be used. For example, some methods known in the art require the use of sheeting with a thickness of 60 mils or less.
Other means and methods for securing and sealing a sheet to a pile are difficult or expensive to perform. Divers and other laborers are expensive to employ and the water environment makes many tasks, which would be otherwise be simple and inexpensive to perform, very difficult and time consuming.
Examples of such prior piling protectors are disclosed in the following U.S. patents: Liddell, U.S. Pat. No. 3,139,731; Liddell, U.S. Pat. No. 3,177,667; Cravens et al., U.S. Pat. No. 3,362,124; Colbert et al., U.S. Pat. No. 4,023,374; Papworth, U.S. Pat. No. 4,068,483; Straub, U.S. Pat. No. 4,252,471; Hellmers, U.S. Pat. No. 4,697,957; Inhofe et al., U.S. Pat. No. 4,713,129; Dokmo et al., U.S. Pat. No. 5,102,265; and Marx et al., U.S. Pat. No. 5,138,806.